Patients are placed on mechanical ventilation for a variety of medical dysfunctions. These include such conditions as: pulmonary distress, chest trauma, cardiac failure, paralysis, neuromuscular failure, multiple organ failure, sepsis leading to pulmonary complications, post-operative management and other conditions. Mechanical ventilators are typically adapted to do two things, provide for ventilation and oxygenation. Ventilation generally includes delivering controlled minute ventilations using sets of tidal volumes and respiratory rates. This can be provided using set pressure or set volume of gas supplied under to the lung. Oxygenation is generally controlled by delivering a level of prescribed oxygen and or positive end expiratory pressure (PEEP) used to increase functional residual capacity (FRC).
Even though the ventilation technology is constantly improving, ventilator dependence is still a serious medical and economic problem. It is well known that severe and sometimes lethal complications may develop the longer a patient is on ventilator support. In addition, as ventilator therapy is provided in specialized and very expensive Intensive Care Unit environments, there is a need to minimize ventilator dependency. Weaning the patients from artificial ventilation is among the most difficult challenges of the regarding intensive care ventilation.
Prior art ventilator weaning monitoring methods are not efficient enough and are often depending on subjective impressions of clinical fatigue or distress and/or arterial blood gas derangements that of necessity measure failure after the failure has already developed. More modem monitoring techniques such as the ratio of Tidal Volume to Respiratory Rate are still relatively crude indices of weaning performance. Weaning from ventilator dependency is potentially hazardous due to unexpected precipitous ventilatory failure, and early warning by appropriate monitoring means is imperative for patient safety. Further, controlled stress of weakened respiratory muscles is imperative in order to recondition these muscles, but in addition to not over-stress these recovering muscles and therefore cause further damage. It is often difficult to safely define the proper degree of weaning stress clinically.
Moreover, when a caregiver (such as a doctor or a nurse) considers weaning a patient from a ventilation machine and/or wishes to monitor the progress of the weaning process, he or she has to take into consideration and often even analyze a great deal of patient related parameters (data). These various parameters may each have different units and occasionally, different units may be used for the same parameter. Moreover, the absolute values of the parameters may not always be intuitive for understanding/interpretation and neither are they linearly proportional to severity of the condition. In addition, some parameters may have different meanings as to the condition of the patient when increasing and/or when decreasing, that is, for some parameters, decrease in the value indicates improvement while with other parameters, decrease in value may indicate deterioration of the patient condition. Thus the complexity and multiplicity of parameters also add to the existing difficulty of weaning initiation and monitoring.
There is thus a need in the art for systems, devices and methods that would allow straightforward monitoring the constantly changing condition of a patient undergoing weaning from ventilation.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the figures.